Pilot iroshizuku color inconsistency

Hi! I’ve been using Iroshizuku inks in a fude nib fountain pen for calligraphy for a while. I love the way the Momiji ink looks with the dark red and the gold. But the color is wildly inconsistent, with the ink being pink with no gold a lot of times. Does anyone have a way to consistently produce the rich dark red color with a lot of gold? Thanks